The present invention relates to coating the interior surfaces of a conduit while it is in place in the situation in which it is to be used. More particularly, the invention relates to treating segmented conduits, such as tubing strings in wells, to provide a corrosion resisting coating throughout all of the interior surfaces, including pipe junctions, and the like.
Various methods and apparatuses for coating various conduits in use locations have been described in U.S. Patents such as the following: U.S. Pat. No. 3,041,204 relates to a method and apparatus for coating pipes or conduits with any desired fluid material, using a fluid-propelled deformable contact head for applying the coating material. U.S. Pat. No. 3,108,012 relates to cleaning, coating, then drying, transmission lines in-situ underground using pumpable barriers forming chambers for receiving the cleaning and treating materials and wiping them along the interior of the line. U.S. Pat. No. 3,355,315 by R. M. Jorda, T. J. Robichaux and N. D. Smith relates to coating pipe interiors with a polyepoxide, preferably by pumping in a solution of a compound possessing amino hydrogen atoms, then a solution containing a polyepoxide, and then allowing the resulting coating to cure along the pipe walls. U.S. Pat. No. 3,394,025 describes a pipe coating apparatus in which coating material is disposed between barrier materials and propelled through the pipe by a fluid pressure behind the barrier members. U.S. Pat. No. 3,598,636 describes coating pipe interiors by pneumatically propelling a coating liquid which is confined between an applicator plug and a retaining plug.